Paper perforating mechanism



Nov. 14, 1961 R, JR 3,008,366

PAPER PERFORATING MECHANISM Filed Jan. 6, 1956 FIG. I.

' FIG. 2. L a 30 46 5052.

////// INVENTOR.

dam, Hm rJZM AZTQPA/EK? United States Patent 3,008,366 PAPER PERFORATINGMECHANISM Ruel E. Taylor, Jr., South Windham, Maine, assignor to HudsonPulp and Paper Corporation, New York, N .Y., a corporation of MaineFiled Jan. 6, 1956, Ser. No. 557,749 6 Claims. (Cl. 83-346) Thisinvention relates to a mechanism for perforating long strips of sheetmaterial along generally equally spaced lines transversely of the edgesof the strip, and more in particular to perforating toilet paper of thehigh quality tissue type.

An object of this invention is to provide an improved perforatingmechanism for a uniform perforated line in paper formed by sharplyarticulated cut and uncut regions, so that the paper can be torn easilyand uniformly along this line without ragged ends. Another object is toprovide such a mechanism which can be adjusted to give optimumperformance at all times, for example, to compensate for variations inthickness. A further object is to provide such adjustment continuously,even during operation. A further object is to provide such a mechanismwhich is self-compensating for wear so that throughout its life it willperforate with substantially the same high efliciency. An additionalobject is to provide perfo rating mechanism of the above character whichis simple in construction and operation, inexpensive to manufacture andmaintain, and adaptable to many conditions of operation and use. Theseand other objects will be in part understood, and in part pointed outbelow.

In making toilet paper, wide sheet strips or Webs first are perforatedalong equally spaced lines transversely of the length of the strips, andthen the wide sheet strip is slit and the individual rolls are formed.The perforations provide for tearing off the short lengths or sheets ofthe final roll.

The prior type of these perforations have been formed by piercing thestock with a row of closely spaced sawtooth elements. However, theresulting perforations have ragged edges which extend above the surfaceof the sheet. More importantly, the perforations are not uniform so thatthe paper tears along one line of perforation, whereas it does not tearunder the same force along another line; and this often causes thelength of strip being torn from the roll to be longer or shorter thanintended. Moreover, with this prior type of perforation, the papersometimes tears partly along one line and partly along another, leavingdangling ends on the roll and on the strip end. The present inventionavoids thesedifiiculties by providing a low cost, long-wearing,trouble-free apparatus which produces a greatly improved perforatedline.

In accordance with the present invention and in the specificillustrative embodiment thereof, a paper web or strip is fed from asupply roll to and through a perforating arbor mechanism where it is cutalong successive lines with an impacting or impact-cut action. Each lineof perforation is produced by a single transverse blade edge mounted-ina unique way on a blade arbor and impacting against and moving with amating lateral row of spaced, annular anvils carried on an anvil arbor.The paper is cut cleanly between the blade edge and each of the anvilsas the paper moves between the arbors, so as to produce 3,008,366Patented Nov. 14, 1961 will best be gained from a study of the followingdescription given in connection with the accompanying drawings in which:

FIGURE 1 is a schematic side view of a paper handling mechanism;

FIGURE 2 is an enlarged fragmentary sectional view on the line 2-2 ofFIGURE 1 with parts broken away; and,

FIGURE 3 is an enlarged sectional view of the perforating arbormechanism on the line 3-3 in FIGURE 2.

The paper handling mechanism shown in FIGURE 1 includes a jumbo supplyroll 11 from which a wide web or strip 12 of paper is drawn to the rightby a pair of rolls 13 and it then passes through the perforatingmechanism 16. Here, the web or strip 12 is perforated along successivetransverse lines and is then led through the slitter blades 14 where itis cut into a number of narrower strips, each equal in width, forexample, to. form toilet paper. After leaving the slitter, it is woundby wind-up mechanism 18 into individual rolls for sale and use.

The details of the perforating mechanism 16 are shown in FIGURES 2 and3. This mechanism includes a top blade arbor 20 andan anvil arbor 22which are rotated in opposite directions, with their adjacent peripheralsurfaces moving together at the substantially same speed. These arborsare positioned closely together, but they do not pinch the web of paperbetween them, and the paper is driven forward by the wind-up mechanism.Arbors 20 and 22 are mounted at their ends in bearings 40 and 42, theright-hand pair of which are shown. These arbors are driven by gears(not shown) upon the left-hand end of the arbors.

Evenly spaced across the surface of arbor 22 are the annular anvils 24which are separated by the shallow annular grooves 26. The web or strippassing between the arbors is cut on the anvils and it is not cut at thegrooves so that a perforated line is made across the strip formed byalternately cut and uncut zones.

As seen in FIGURE 3, arbor 20 carries evenly spaced around its surfacein elongated pockets or housing, four cutting blades 28, each of whichhas a straight edge 30 resiliently urged radially outwardly andpositioned slight-.

ly beyond the surface of arbor 20. Thus, with the arbor 20 in theposition shown, a blade edge 30 impacts the strip 12 against anvils 24and cuts a slit opening in the strip. In the course of making aperforated line, the strip is pushed into the grooves between the anvilsand the paper remains uncut at these areas.

Each blade 28 is in the form of asquare bar with sharp corner edges. Theblade rides against a pair of slides or gibs 32 which are mountedlengthwise in slots in arbor 20 and form'a V shaped support with anarrow sli-t between their adjacent ends through which edge 30protrudes. Each of the gibs 32 has threaded into it a plurality of setscrews having conical ends which are received in similarly shapedrecesses in the arbor. During installation, each gib is put intoposition, and then its set screws are tightened so as to push the gibradially ou-twardly with respect to the axis of the arbor. This pressesthe gib againstthe side of the slot and away from the bottom of theslot. In this way, the width of slit is accurately determined, and thegibs are rigidly held in position. :Each blade 28 is urged against itsassociated gibs by an air-filled expandabletube 34. Hence, the blade isresiliently held in the position shown, but it may be moved radiallyinwardly away from gibs 32 and so that edge 30 no longer protrudesbeyond the arbor surface. The air pressure in this tube isadjustable andcontrols the force exerted upon the blade, and the force with which theedge 30 bears against the sheet stock and the anvils.

Referring to FIGURE 2, each'tube 3 4 is mounted at its ends in a pair ofblocks 44 (only one of which is shown) which are held in place by setscrews 45. Each of these blocks has an opening 46 into which the end ofthe tube is anchored by an internal. cylinder 48. The cylinder at theleft is not shown, but it is solid so that it seals the end of the tube.The cylinder 48 at the right has a central opening 50. therein which isin: alignment with a bore 52 in block 44. Bore 52 is connected by a bore36 and a bore extension 37 to an axial bore 38 in the arbor. shaft 54,.which extends throughrthe bearing 49 and provides an attachment for anair line 56. Thus,

the air pressure in each tube 34 can be controlled externally while thearbors are in motion.

It has been indicated above that cutter blades 28 are square incross-section, and each of the four edges on each blade is a cuttingedge. Accordingly, when an edge of a blade becomes dull the arbors arestopped and the tube 34 for the blade is exhausted of its air so thatthe blade is no longer held rigid. The blade is then easily turnedwithin its pocket to a position wherein another edge 30 protrudes fromthe cutter slot. Hence,

the cutting edges are easily changed, and each blade maybe kept incontinuous service until all four of its edges require sharpening.

While arbors 20 and 22 are driven in unison at substantially the samespeed, arbor 2G is driven slightly faster than arbor 22. Thus, duringeach rotation, blade edge 30 contacts a different line on the anvils 24than it did the previous rotation, and this avoids abnormal wear on theanvil. Arbor 22 is is advantageously made of steel that can be surfacehardened thereby reducing wear, and blades '28 are hardened steel,illustratively, one-half inch square. The circumference of the arbors 20and 22 in this unit is about 1-8 inches, and they can be driven at up to1000 feet per minute. As the speed of these arbors increases, less airpressure in tubes 34 is required for a proper cut because of theincrease in centrifugal force on blades 28. The scuffing action betweenblades 28 and arbor 22 caused by slight differences in surface speedbetween blade edges 30 and arbor 22 and by the slight relative movementof the blades in their housings or pockets in arbor 20, may improve thecutting action. During each cutting action, the blade is pushed backsomewhat toward or to the surface of arbor 20, but the resilient actionof the air tube 34' permits this and yet insures a good cutting action.

In the specific illustrative embodiment of the invention hereindisclosed, substantially eighty percent of the fibers along theperforated line are cut so that the web is held together by theremaining twenty percent. It has been found that this gives excellentresults from the standpoint of avoiding an accidental tearing of the webor the individual strips after the slitting operation. Also, the web iscut suflicientlyat each perforation to permit easy tearing. Theparticular manner of cutting permits very accurate control and, asindicated, all of the perforated lines are susbtantially identical fromthe strength standpoint.

The present invention permits great flexibility in the percentage of cutfibers and in the number and sizes of the slits which form theperforations; For example, arbor 22 may be easily removed and replacedby another arbor'having more or less anvils of greater or less width,and the grooves between'the anvils may be of a diiferent width.

' In the illustrative embodiment, there are four cutter blades, but theinvention contemplates that more or less such blades may be used. Forexample, for some con- V 4 or sheet form which is not interfered with bythe perforating mechanism.

It has been indicated above that the arbors 20 and 22 are driven atslightly different speeds. The invention contemplates that this drive isaccomplished, illustratiyely, by driving one of them directly, and bydriving the other one indirectly vthrough a pair of inflated tires.Illustratively a pair of such tires is mounted in contactingrelationship upon the ends of the two arbors, and the tires areinflated, but at slightly different pressures. Hence, the one roll isdriven from the other, but the tire which is inflated with the greaterpressure has the greater efiective periphery; the other tire with thelesser pressure, therefore, has its arbor turned at a slightly slowerspeed. In the illustrative embodiment of the invention, the web is slitprior to rewinding, but the invention contemplates winding the web intolong rolls and then cutting the long rolls into lengths to form theindividual rolls of toilet paper.

The above description of the invention is intended in illustration andnot in limitation thereof. Various minor changes or modifications of theembodiment illustrated may occur to those skilled in the art and thesecan be made without departing from the spirit or scope of the inventionas set forth.

I claim:

1. A high speed mechanism for perforating webs of paper and the like,said mechanism including a cutter arbor mounted for rotation around anaxis, said arbor having a cavity along its length parallel to and spacedradially outward from said axis, said cavity being defined by opposedabut-ments disposed at generally equal but opposite angles relative to aradius of said arbor to provide a substantially V-shaped seat havingsmooth faces thereon, the apex of the V being cut away to form a slot, astraight bar-like cutter blade having, at least two inclined face-swhich intersect and form a cutting edge, said blade being positioned onsaid smooth surfaces in said cavity with said cutting edge projectingbeyond said slot, anvil means closely opposite said arbor and having asurface movable in the same general direction as said blade adjacentsaid web to support said web during cutting, compressible resilientmeans urging said blade outward against said abutments and permitting itto move inward simultaneously throughout its length and to rock aboutits axis when the edge of said blade strikes against the web, and meansto rotate said arbor at high speed, the mass of said blade, the radialdistance it is mounted from the axis of said arbor, and the speed ofsaid arbor being such that said blade cuts said web by impactthereagainst, whereby said web is cleanly cut and said blade stays sharpfor a considerable time.

2. The mechanism in claim 1 wherein said compressible resilient meansincludes a pneumatic tube mounted behind said blade and conforming tothe shape thereof.

3. The mechanism in claim 1 wherein said blade has a plurality ofcutting edges, said abutments comprising gibs, at least one of which isremovable to permit removal of said blade.

4. A high speed mechanism for perforating webs of paper andthe like,said mechanism including a cutter arbor mounted for rotation around anaxis, said arbor having a plurality of cavities along its lengthparallel to and spaced radially outward from said axis, each of saidcavities being defined by opposed removable gibs disposed at generallyequal but opposite angles relative to a radius of said arbor to providea substantially V-shaped seat having smooth faces thereon, the apex ofthe V being. cut away to form a slot, a plurality of straight bar-likecutter blades each having at least two inclined faces which intersectand form a cutting edge, each blade being positioned in a respectivecavity on said smooth surfaces with said cutting edge projecting beyondsaid slot, an anvil arbor rota-tablly mounted closely opposite saidcutter arbor to support said web during outing, a plurality ofexternally controlled pneumatic tubes, each tube positioned behind arespective one of said blades and urging said blade outward against saidgibs and permitting it to move inward simultaneously throughout itslength and to rock about its axis when the edge of said blade strikesagainst the Web, and means to rotate said otter and anvil arbors at highspeed, the mass or" each blade, the radial distance it is mounted fromthe axis of said cutter arbor, and the speed of said cutter arbor beingsuch that said blades out said web by impact thereagainst, whereby saidWeb is cleanly cut and said blades stay sharp for a considerable time.

5. The mechanism in claim 4 wherein said anvil arbor is rotated at aslightly different speed than the speed of said cutter arbor.

6. The mechanism as described in claim 1, wherein said anvil means isformed by an anvil arbor having a plurality of axially-spaced annulargrooves with annular anvil surfaces therebetween.

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